Who do you listen to?

If you're married and your spouse wasn't the first name that came to mind, well, that's a different column.

In business, who do you listen to?

Experts? Family? Customers? Peers?

If you're successful in business or as an entrepreneur, you likely listen to at least a few people in each of those categories. And others.

But in marketing, peers are the movers of decision making. You may listen to your customers or experts (or your spouse) but when it comes time to make a business decision, peers carry the day. And the more connected and networked we all become, the more peer to peer marketing (P2P) is the future of reaching people.

The reasons are pretty obvious: we tend to add more weight to the opinions of those with experience or goals like ours. Also as powerfully, we don't want to be left behind. If Bill or Brenda or Bob is trying a new place or product, we usually at least consider giving it a look ourselves.

Why that's important is because we--all of us--are in a world of information overload. Facebook can tell us what our friends and family are doing nearly every second. Baby photos and viral videos are a screen tap away. At the same time it seems as though everyone in the world is an expert in something now. Books, TV appearances, blogs, and micro-blogs--everyone has at least two of them. It's beyond overwhelming.

But peers cut though the chaos. It's the secret behind the explosion of LinkedIn. In what seems like the blink of an eye, LinkedIn has gone from an online resume posting service to an indispensable marketing tool because it's where business peers interact with business peers.

You may get more 'likes' on Facebook. But if you're after action--like buying--instead of eyeballs, P2P communication is working. "When we started and up until a year ago, all that we had to rely on was peer to peer (P2P) marketing. It has been an essential catalyst to our explosive growth from $300 million in assets to $4.5 billion in less than 5 years," said Provident Trust Group Chief Executive Officer Theresa Fette.

As a marketing decision, it's going to be (it is already, I'd say) absolutely essential to find P2P networks on LinkedIn and in real world places such as conventions and business happy hours. Breaking into those circles and getting some early adaptors to tell their friends is more efficient and more effective than just about anything else you can do.

In other words, P2P marketing is what word of mouth used to be--when neighbors chatted about their experiences with businesses and products. Or when organizations such as Good Housekeeping or the Better Business Bureau lent their good names to products and services worth trying. "Peer-to-peer endorsements are the strongest form of advertising a business or brand can obtain." Says Vapor4Life CMO Hank Ostholthoff "Today, peer endorsements are spread digitally through engaging pieces of content on social feeds, snaps, group text or a forward email chains with friends.. The job of every marketer is to create content that resonates with people and is worth sharing in like-minded networks. Be bold, be real and hopefully you'll be remarkable."

Now, that seal of approval is coming from peers--those whose input we value above the organizations and experts we can't get away from.

Cracking the code on P2P marketing--as LinkedIn has started to--looks like it's going to be the fast lane to future of highly efficient customer engagement. Be among the first to do that and you'll be wise, and wealthy. And, chances are, make your spouse very proud.